Systems and Methods for Preparing Bone Voids To Receive A Prosthesis

ABSTRACT

A method of implant a knee prosthesis includes forming a bone void at an end of a bone, implanting a void filler in the bone void, and implanting a knee prosthesis onto the end of the bone so that a stem of the knee prosthesis is received by the void filler.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.15/597,851, filed on May 17, 2017, which is a continuation of U.S.application Ser. No. 14/837,437, filed Aug. 27, 2015, now U.S. Pat. No.10,213,215, which is a continuation of U.S. application Ser. No.13/730,082, filed Dec. 28, 2012, now U.S. Pat. No. 9,149,282, whichclaims the benefit of the filing date of U.S. Provisional ApplicationNo. 61/581,736, filed Dec. 30, 2011, all of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to surgical instruments for preparing abone to receive a joint prosthesis system, and in particular to guidedsurgical reaming instruments and bone void fillers for use in total kneereplacement revision procedures.

BACKGROUND OF THE INVENTION

Joint replacement surgery is a common orthopedic procedure for jointssuch as the shoulder, hip, knee, ankle and wrist. Prior to implantingprosthetic components in a joint of a patient, a surgeon generally hasto resect at least a portion of the patient's native bone in order tocreate a platform and/or recess or cavity for receiving at least aportion of the prosthetic components being implanted. During the processof resecting bone, a surgeon typically makes an effort to only resectthe amount of bone that is needed in order to implant the prostheticcomponents properly. In other words, it is generally the goal tomaintain as much native bone within the joint.

When prosthetic components fail for any one of a variety of reasons, arevision procedure is often necessary. Although defects in a boneadjacent a joint, such as the hip or knee, may occur naturally due towear and arthritis of the joint and congenital deformities, the removalof a failed prosthetic component also creates an issue with maintainingnative bone. Specifically, when prosthetic components are removed fromthe joint during a revision procedure, it is common for there to havebeen further native bone loss in the area adjacent the original implantposition of the prosthetic components due to movement of the componentsafter implantation or even further degeneration of the bone. Forinstance, when bone voids are observed in either the proximal tibia ordistal femur, or both, after removal of a previously implantedcomponent, it is standard surgical practice to fill those voids as partof the surgical procedure. One way of filling those voids is to useweight bearing void fillers, typically made of an implant-grade metalsuch as titanium. Such void fillers may be referred to as metaphysealreconstruction devices (MRD). The name MRD reflects functions such asweight bearing that these devices generally provide.

Because voids in bone are typically irregular in shape, preparation ofthe bone void area is typically required prior to implantation of a MRD.This preparation (typically by reaming, broaching or milling) ensuresthere is sufficient room in the bone cavity for the MRD. An accurate fitbetween the shaped bone cavity and the MRD is important for establishingjoint line, and allowing for weight bearing and bone remodeling duringthe recovery process.

Different methods may be employed to attempt to prepare the bone voidarea to create an accurate fit between the shaped bone cavity and theMRD. One method is to ream along the intramedullary (IM) axis, followedby broaching. Another method is to ream on the IM axis, followed byfreehand burring or bone removal using a rongeur, which may also befollowed by broaching. With these methods any reaming performed occurson the IM axis only, so that void areas at a distance from the IM axis,which commonly occur, can only be resected using manual methods. Also,freehand bone removal, either powered or unpowered, such as by burr orrongeur, often does not produce accurate cavity shapes to receiveprosthetic components having predefined configurations. A typical resultof the above mentioned methods is that areas remain where the outerwalls of the MRD do not contact the cavity, which may lead toundesirable stress distribution and possible loss of bone regrowth. Alsotypical is the time consuming requirement of iterative bone removal,with multiple checks against the MRD, to obtain a correct fit.

Therefore, there is a need for a surgical instrument that createsaccurate bone cavity geometries and minimizes the necessity for freehandbone removal. There is also a need for enabling surgeons to create bonecavities offset from the IM canal with a fully guided system.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, a device forimplantation into a bone void. The device comprises a sidewall defininga cavity for receipt of a portion of a joint prosthesis. The devicefurther comprises a selectively removable portion formed in thesidewall, wherein removal of the selectively removable portion forms agap in the sidewall.

In another embodiment, the device may include a first body having afirst sidewall and a first cavity defining a first longitudinal axis.The device may further include a second body connected to the firstbody. The second body has a second sidewall and a second cavity incommunication with the first cavity. The second cavity defines a secondlongitudinal axis, wherein at least one of the first and secondsidewalls includes the selectively removable portion and removal of theselectively removable portion forms a gap in the respective sidewall.

In another aspect of the present invention, the device may include anadhesive anti-rotation feature connected to the inner surface of thefirst body.

The anti-rotation feature may be realized in the form of a plurality ofprotrusions radially extending into the cavity from the inner surface ofthe first body.

According to another aspect of the present invention, the first body mayinclude a clearance channel extending through the first sidewall forminga gap for receipt of a portion of the prosthesis.

The first body may be realized in a form that is substantiallyfrustoconical, such that a proximal end has a larger diameter than adistal end of the first body.

In one embodiment, the first body may include a neck extending from thedistal end of the first body for stabilizing the device in the bone.

The first body and second body may be realized where each have an innersurface made from a solid biocompatible material and an outer surfacemade from a porous biocompatible material.

Further, the selectively removable portion may be realized where it ismade entirely of the porous biocompatible material.

Yet another aspect of the present invention is a surgical system forforming a void in a bone. The surgical system includes a support memberconfigured to be securely positioned within an intramedullary canal ofthe bone. Further, the surgical system includes an offset guide memberhaving a longitudinal axis. The offset guide member is configured toattach to the support member so that the longitudinal axis of the offsetguide member is in a fixed and offset relation with the intramedullarycanal of the bone. Additionally, the surgical system includes a cuttingmember for forming an offset bone void having a cutting head attached.The cutting member is configured to slidably engage the offset guidemember along the longitudinal axis of the offset guide member.

In one embodiment, the support member includes radially projectingflanges extending outward from the proximal end of the support member.Further, the offset guide member includes a cannulated distal end. Thecannulated distal end has an inner surface and radially extendingflanges extending inward from the inner surface and is configured toengage the radially projecting flanges of the support member.

In another embodiment of the present invention, the support member maycomprise a cone trial and a guide shaft. The cone trial is configured tobe securely inserted into a central bone void, and the guide shaft isconfigured to securely connect to the cone trial such that distal androtational movement is prohibited.

Further, the offset guide member may have a locking body and a cuttingguide component. The locking body is configured to lock the offset guidemember to the guide shaft. The cutting guide component has alongitudinal axis and is configured to slidably receive the cuttingmember along the longitudinal axis of the cutting guide component. Thecutting guide component is fixed to the locking body, wherein lockingthe locking body to the guide shaft fixes the longitudinal axis of thecutting guide component in an offset relation to the intramedullarycanal of the bone.

In another aspect of the present invention, the offset guide member mayinclude an offset driver. The offset driver includes a longitudinal axisand is configured to attach to the support member so that thelongitudinal axis of the offset driver is in a fixed and offset relationwith the intramedullary canal of the bone. The offset guide memberfurther includes an offset driver sleeve having longitudinal axis and isconfigured to slide over and attach to the offset driver so that thelongitudinal axis of the offset driver sleeve is in an offset and fixedrelation with the longitudinal axis of the offset driver and theintramedullary canal of the bone.

In one embodiment, the cutting member may be a broach. Additionally thesurgical system may further comprise a second stage broaching toolconfigured to slidably engage the offset guide member along the offsetlongitudinal axis of the offset guide member. The second stage broachingtool is shaped to substantially conform to the shape of a bone voidfilling device.

In another embodiment, the cutting member may be a reamer.

According to another aspect of the present invention, a surgical methodfor forming a void in bone. The surgical method comprises the step ofpositioning a support member securely within an intramedullary canal ofa bone. The method further includes the step of attaching a guide memberhaving a longitudinal axis to the support member in a fixed and offsetrelation to the intramedullary canal.

Additionally, the method includes connecting a cutting member having acutting head to the guide member in a slidable arrangement along thelongitudinal axis of the guide member such that the cutting head faces afirst bone segment. Further, the method comprises cutting the first bonesegment along the longitudinal axis of the guide member, thereby forminga first offset bone void.

In one embodiment, the cutting member may be a reamer.

In another embodiment, the cutting member may be a broach.

Another aspect of the present invention, the method further includes thestep of detaching the guide member and cutting member from the supportmember. Further still, the method comprises a step of reconnecting theguide member and cutting member to the support member so that thecutting head faces a second bone segment. Additionally, there is a stepof cutting the second bone segment along the longitudinal axis of theguide member, thereby forming a second offset bone void.

In one embodiment of the method, the method may comprise the step ofdisconnecting the cutting member from the guide member. Further, theremay be a step of attaching a guide member sleeve having a longitudinalaxis to the guide member so the longitudinal axis of the guide membersleeve is offset and fixed with respect to the longitudinal axis of theguide member and intramedullary canal of the bone. Additionally, themethod may include a step of connecting a cutting member to the guidemember sleeve in a slidable arrangement along the longitudinal axis ofthe guide member sleeve so that the cutting head faces a second bonesegment. There is also a step of cutting the second bone segment alongthe longitudinal axis of the guide member sleeve, thereby forming asecond offset bone void.

A further aspect of the present invention, the method may include thestep of detaching the guide member, guide member sleeve, and cuttingmember from the support member. Further, there may be a step ofreconnecting the guide member, guide member sleeve, and cutting memberto the support member such that the cutting head faces a third bonesegment. Additionally, the method may include cutting the third bonesegment along the longitudinal axis of the guide member sleeve, therebyforming a third offset bone void.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an assembled perspective view of a two part reamer and adriver having longitudinal axes thereof in alignment.

FIG. 2A shows a perspective view of an IM reamer in conjunction with analignment guide cutting jig being used to determine an offset axis.

FIG. 2B shows an exploded perspective view of an IM reamer inconjunction with a cutting block being used to determine an offset axis.

FIG. 3A shows an assembled perspective view of an IM reamer and a driverhaving an offset adapter.

FIG. 3B shows an exploded perspective view of the IM reamer and theoffset driver shown in FIG. 3A.

FIG. 4A shows an exploded perspective view of an offset reamer, anoffset driver and an IM reamer.

FIG. 4B shows an assembled perspective view of the offset reamer, theoffset driver and IM reamer shown in FIG. 4A.

FIG. 5A shows an exploded perspective view of an offset reaming guide,an offset driver, and an IM reamer.

FIG. 5B shows an enlarged exploded perspective view of the offsetreaming guide and the offset driver shown in FIG. 5A.

FIG. 5C shows an assembled perspective view of the offset reaming guide,the offset driver, and IM reamer shown in FIG. 5A.

FIGS. 5D-E show perspective views of the assembly shown in FIG. 5C infirst and second configurations.

FIG. 6A shows an exploded perspective view of an inline driver, aconical reaming tool, an offset reaming guide, an offset driver and anIM reamer.

FIG. 6B shows an assembled perspective view of the conical reaming tool,the offset reaming guide, the offset driver and IM reamer shown in FIG.6A.

FIG. 7A shows an exploded perspective view of an offset broaching tool,an offset driver and an IM reamer.

FIG. 7B shows an assembled perspective view of the offset broachingtool, the offset driver and IM reamer shown in FIG. 7A.

FIGS. 8A-C show different enlarged perspective views of a second stagebroaching tool.

FIG. 9A shows an assembled perspective view of a femoral implant in anunlocked position.

FIG. 9B shows an assembled perspective view of a femoral implant in alocked position.

FIG. 9C shows an exploded perspective view of a femoral component, voidadapter, offset component, stem, and MRD.

FIG. 9D shows an assembled perspective view of a locked femoral implantwith an MRD locked into place.

FIG. 9E shows an assembled front view of the locked femoral implant andMRD shown in FIG. 9D.

FIG. 9F shows a front view of one embodiment of a femoral MRD.

FIG. 10A shows an front view of one embodiment of an IM reamer.

FIG. 10B shows a bushing assembled with the IM reamer of FIG. 10A.

FIG. 10C shows a cylindrical reamer assembled with the IM reamer of FIG.10A.

FIG. 11 shows a perspective view of one embodiment of a diaphysealfemoral cone.

FIGS. 12A-B show front and perspective views of an offset bushingattached to the IM reamer of FIG. 10A.

FIGS. 12C-D show front and perspective views of a conical reamerattached to the instrument of FIGS. 12A-B.

FIG. 13 shows a perspective view of one embodiment of a metaphysealfemoral cone.

FIG. 14 shows a front view of a preparatory reaming step of a tibiabone.

FIG. 15 shows a front view of a cone reamer being prepared for a firstreaming step.

FIG. 16 shows a front view of a first reaming step using the cone reamerof FIG. 15.

FIG. 17A shows a front view of a cone trial and reamer guide shaft beingprepared for a placing step.

FIG. 17B shows a perspective view of the cone trial.

FIG. 17C shows a perspective view demonstrating an interrelation betweenthe cone trial and reamer guide shaft.

FIG. 18A shows a front view of a placing step and a template guide andsizing template being prepared for a first seating step.

FIG. 18B shows a perspective view of the sizing template and templateguide of FIG. 18A.

FIG. 19 shows a perspective view of the cone trial, template guide,sizing template, reamer guide shaft and bone after the first seatingstep has been completed.

FIG. 20A shows a perspective view of an offset lobe reamer retainer andoffset lobe reamer being prepared for a second reaming step.

FIG. 20B shows a front view of further preparation of the offset lobereamer and lobe reamer guide for a second reaming step.

FIG. 21 shows a front view of the surgical reaming system and tibia boneafter the second reaming step.

FIGS. 22A-B show a top and front view of a conical cone, respectively.

FIGS. 22C-D show a front and side view of an interrelation between theconical cone and a baseplate and baseplate keel.

FIG. 22E shows a transparent view of an interrelation of the conicalcone with the baseplate and baseplate keel when the conical cone is deepwithin bone.

FIG. 22F shows a transparent view of an interrelation of the conicalcone with the baseplate and baseplate keel when the conical cone isshallow within bone.

FIGS. 23A-C show a perspective, top, and front view of a lobed cone,respectively.

FIG. 23D shows a bottom view of an interrelation between a lobed coneand baseplate keel, particularly the relationship of the baseplate keelwith regard to a lobe and clearance channel of the lobed cone.

FIG. 23E shows a transparent view of an interrelation of the lobed conewith the baseplate and baseplate keel when the lobed cone is deep withinbone.

FIG. 23F shows a transparent view of an interrelation of the lobed conewith the baseplate and baseplate keel when the lobed cone is shallowwithin bone.

FIG. 23G shows an interrelation between the lobed cone and a stem of aprosthesis.

DETAILED DESCRIPTION

As used herein, when referring to the surgical reaming instruments ofthe present invention, the term “proximal” means closer to the surgeonor in a direction toward the surgeon and the term “distal” means moredistant from the surgeon or in a direction away from the surgeon. Theterm “anterior” means towards the front part of the body or the face andthe term “posterior” means towards the back of the body. The term“medial” means toward the midline of the body and the term “lateral”means away from the midline of the body.

FIG. 1 illustrates a side view of a two part reamer 100. The two partreamer consists of an IM reamer 102 and inline driver 104. In theassembled position as shown, longitudinal axes of the IM reamer 102 andinline driver 104 are coaxial. In a revision procedure, the initial stepafter removing the prosthesis located in the bone is to ream the bonegenerally along a longitudinal axis thereof. In total knee revisionprocedures, for example, the bone is preferably reamed along the IMcanal. This can be accomplished, for example, by the use of two partreamer 100. Once the initial IM reaming step is completed, it may bedetermined that the patient would benefit from a MRD implanted along anaxis of the bone offset from the IM axis created in the initial reamingstep. To prepare the bone to accept such an MRD, another drilling stepmay be performed on the desired axis for MRD implantation.

FIGS. 2A and 2B illustrate different methods for determining the desiredposition of the offset axis. Referring to FIG. 2A, an alignment guidecutting jig 200 is shown. The alignment guide cutting jig 200 can beused to determine the desired location of the offset axis in the bone.Generally, alignment guide cutting jig 200 is used with an adapter (notshown). FIG. 2B shows a cutting block 202 being used in conjunction withthe inline driver 104 of the two part reamer 100 to align the offsetaxis desired for bone 204. Once the desired location for the offset axisis chosen, the position is recorded and the proper offset driver 300(discussed below) is chosen to achieve the desired offset axis.

FIGS. 3A and 3B show an embodiment of an offset driver 300 having ashaft 302 with a longitudinal axis and an adapter end 304 with alongitudinal axis offset from the longitudinal axis of the shaft 302.FIGS. 3A and 3B show offset driver 300 before and after engagement withthe IM reamer 102. As illustrated in FIG. 3A, the offset driver 300includes a shaft 302 that is offset from the axis of the IM reamer 102,and thus offset from the axis of the IM canal. The offset driver 300further includes an adapter end 304 at the distal end of the offsetdriver 300. The adapter end 304 can be at least partially hollow toengage a proximal end of the IM reamer 102. As illustrated in FIG. 3B,the distal end of the offset driver 300 and the proximal end of the IMreamer 102 can include features to help create a secure engagementbetween the two. For example, the adapter end 304 of offset driver 300can include a plurality of radially projecting flanges 306 spacedcircumferentially around the hollow inside of the adapter end 304. Thevoid spaces between radially projecting flanges 306 can be designed tomate with a set of complementary radially projecting flanges 106 at theproximal end of the IM reamer 102. Once the offset driver 300 issecurely engaged to the IM reamer 102, the surgical instrument can befurther prepared to ream and/or broach the bone.

Referring now to FIG. 4A, an exploded view of an offset reamer 400,offset driver 300, and IM reamer 102 is shown. The offset reamer 400includes a reaming head 404 and reaming shaft 402. The reaming shaft 402and reaming head 404 are coaxial with the shaft 302 of the offset driver300, and thus are also offset from the axis of the IM reamer 102. Asseen in FIG. 4B, a hollow inner cylinder of offset reamer 400 is slippedover the shaft 302 of offset driver 300 to position the reaming head 404coaxial with the desired offset reaming axis as determined, for example,using a technique described with reference to FIG. 2A or 2B. At thispoint, the user can use the offset reamer 400 to create the first offsetbone cavity in preparation for MRD implantation.

Once the first offset bone cavity is created, the offset reamer 400 canbe removed and the surgical instrument can be further prepared to createmedial and lateral bone cavities to create a void space fullycomplementary with a structure of one embodiment of an MRD. FIG. 5Ashows an exploded view of an offset reaming guide 500, offset driver300, and IM reamer 102 for optionally forming additional bone cavitiesthat are offset from the offset bone cavity formed by the offset reamer400. Offset reaming guide 500 includes an offset reaming guide shaft 502and reaming guide base 504. As seen in FIG. 5B, the distal end ofreaming guide base 504 can include groove members 508 for locating andengaging with complementary groove members 308 on the proximal end ofoffset adapter end 304. The groove members 508 of the reaming guide base504 may be symmetric about the longitudinal axis of the hollowcylindrical interior 510 of the offset reaming guide 500. Thisconfiguration allows the offset reaming guide 500 to be slipped over theshaft 302 of the offset driver 300 and engage the complementary groovemembers 308 of the offset adapter end 304 in more than oneconfiguration. For example, a first engagement position of the offsetreaming guide 500 can align the offset reaming guide shaft 502 forpreparation of a bone cavity on the medial side of the first offset bonecavity created with offset reamer 400. The same offset reaming guide 500can then be disengaged from the complementary groove members 308 of theoffset adapter end 304, rotated 180 degrees, and then used to re-engagethe complementary groove members 308 of the offset adapter end 304. Inthis second engagement position, the offset reaming guide shaft 502 canbe aligned on the lateral side of the first offset bone cavity createdwith the offset reamer 400.

FIG. 5C illustrates the offset reaming guide 500 engaged with the offsetdriver 300 in a first engagement position. To further illustratedifferent alignment capabilities of the offset reaming guide 500, FIG.5D illustrates a first medial reaming engagement position of the offsetreaming guide 500, while FIG. 5E illustrates a second lateral reamingengagement position of the offset reaming guide 500. In these figures,the IM reamer 102 is shown in isolation for simplicity of illustration.However, in practice the IM reamer 102 would be engaged within a boneand an operator could change the offset reaming guide 500 from theposition shown in FIG. 5D to the position shown in FIG. 5E withoutremoving the IM reamer 102 from the bone. While not shown, the offsetreaming guide 500 can be set in a plurality of different positionsdepending on the choice of the operator.

After the reaming guide 500 engages the offset driver 300, the surgicalinstrument can further be prepared for creating another cavity in thebone, such as a medial or lateral bone cavity that is offset medially orlaterally from the offset bone cavity created by the offset reamer 400.FIGS. 6A and 6B show exploded and assembled views of the surgicalinstrument prepared for creating conical bone cavities, such as medialand lateral bone cavities. As can be seen in the figures, the IM reamer102, offset driver 300, and offset reaming guide 500 are assembled asseen in FIGS. 5A-E. A conical reamer 600, including conical reamer shaft602, conical reaming head 604 and conical reamer shaft cavity 610, isslipped over offset reaming shaft 502. The proximal end of conicalreamer shaft cavity 610 (best seen in FIG. 6B) can include a matingpattern, such as a hexagon, to engage a driver mechanism 650. The drivermechanism (only shown in FIG. 6A) includes a driver shaft 652 and adriver base 654. The distal end of driver base 654 can include a pattern660, such as a hexagon pattern, that is complementary to the matingpattern on the proximal end of conical reamer shaft cavity 610. Thesecomplementary patterns can provide a secure engagement to improve theconnection between the driver 650 and conical reamer 600 when the driver650 is driving the conical reaming head 604 through a bone. The operatorof the surgical device may drive the conical reamer 600 over the offsetreaming guide 500 and into a bone of a patient to create a first conicalbone cavity, for example, on the medial side of the initial cylindricalbone cavity created with the offset reamer 400. After the first conicalbone cavity is completed, the operator may disengage the offset reamingguide 500 from the adapter end 304 of the offset driver 300, and rotatethe reaming guide 500 to a second desired position. After re-engagingthe reaming guide 500 to the adapter end 304 of the offset driver 300,the operator can create a second conical bone cavity, for example, onthe lateral side of the initial cylindrical bone cavity created with theoffset reamer 400.

Besides reaming, broaching is an alternative method of preparing afemoral bone cavity. Referring now to FIG. 7A, an exploded view of anoffset broaching tool 700, offset driver 300, and IM reamer 102 isshown. The offset broaching tool 700 includes a broaching head 704 andbroaching shaft 702. The offset broaching shaft 702 and broaching head704 are generally coaxial with the shaft 302 of the offset driver 300,and thus are also offset from the axis of the IM reamer 102. As seen inFIG. 7B, a hollow inner cylinder of offset broaching tool 700 is slippedover the shaft 302 of offset driver 300 to position the broaching head704 coaxial with the desired offset reaming axis as determined, forexample, by using a technique described with reference to FIG. 2A or 2B.Once offset broaching tool 700 is in position over the offset driver300, a first offset bone cavity can be created in the bone. After thisfirst offset bone cavity is created, the broaching tool 700 can beslipped off the offset driver 300 and the surgical tool can be furtherprepared to create additional bone cavities, such as medial and lateralbone cavities.

Referring now to FIGS. 8A-C, different views of a second stage broachingtool 800 are shown. In these figures, the IM reamer 102 is not picturedand the second stage broaching tool 800 has already been slipped overthe offset driver 300. The adapter end 304 of the offset driver 300 isalso omitted from these views for clarity of illustration. Second stagebroaching tool 800 generally includes a shaft 802 and second stagebroaching head 804. The second stage broaching head 804 includes acentral cylinder shape 805 and a shape comprising two intersectingcones. The two intersecting cones generally correspond to a lateral side806 and medial side 807 (posterior lateral and posterior medial sidesbest seen in FIG. 8C) of bone cavities to be created in the bone. Oncethe second stage broaching tool 800 is in place over the offset driver300, as seen in FIGS. 8A-C, an operator of the surgical device cancreate medial and lateral bone cavities about the first offset bonecavity created with the first offset broaching tool 700, creating a bonecavity that defines the femoral MRD implant geometry with minimal boneremoval steps.

Referring now to FIGS. 9A-E, different embodiments of a femoralconstruct 900 are shown. FIG. 9A shows a perspective view of femoralconstruct 900 of the unlocked variety. The femoral construct 900generally includes a femoral component 902, offset component 904, andstem 906. An embodiment of a femoral construct 900 of the locked varietyis shown in FIG. 9B. In this embodiment, the femoral construct 900further includes a void adapter 908. Both locked and unlocked femoralconstructs 900 are capable of accepting the same MRD, such as MRD 910,for example. In such circumstance, the locked femoral construct 900 isadapted to mechanically lock the MRD 910 to a femoral implant prior toimplantation. On the other hand, where the unlocked femoral constructwould be used in conjunction with the MRD 910, the MRD would typicallybe implanted into the corresponding bone cavity prior to implantation ofthe femoral implant, and would be optionally joined together by use ofadhesive, rather than being mechanically locked. An assembled lockedfemoral construct 900 is shown in FIG. 9D with the MRD 910 attached.

As best seen in the exploded view of a locked femoral construct 900 inFIG. 9C, the void adapter 908 can include an external hexagon featurefor accepting a wrench for locking the final position of the offsetcomponent 904. The distal end of void adapter 908 can also include amale taper with an outer diameter greater than the distance between twodiametrically opposed vertices of the hexagon shape. This allows afemale taper of the MRD 910 to pass over the external hexagon feature ofthe void adapter 908 during assembly. Further, the void adapter 908 caninclude a left hand thread on the axis to male taper sized to accept athread of the offset component 904 to act as a locking nut.

While the femoral construct of the locked variety can include a MRDmechanically locked to a femoral implant with the use of a taper lockfeature (best seen in FIG. 9B), the femoral construct of the unlockedvariety can be assembled with the use of bone cement at the time ofimplantation, for example. Both locked and unlocked femoral constructscan use the same MRD. The locked MRD can be assembled to the femoralcomponent 902 before implantation. The unlocked MRD can be implantedbefore assembly of the femoral component 902. As seen in FIG. 9F, theMRD 910 can include a unique surface cross-section that providesimproved load distribution to bone.

In a further embodiment of the invention, a first group of drillingsteps can be performed to create a first cylindrical void spacegenerally coaxial with the IM canal. Following this first group ofsteps, a femoral implant with a diaphyseal femoral cone 1100 (discussedbelow), that is generally frustoconical, can be implanted into thepatient along the bone cavity created in the first group of steps.Alternatively, if the surgeon or other medical professional decides afemoral implant with a metaphyseal femoral cone is more appropriate, asecond group of steps may be performed, building on the first group ofsteps, to create an appropriate bone cavity.

Referring now to FIGS. 10A-C, there are shown instruments used in thefirst group of steps described above. In a first step of a revisionprocedure, an IM reamer 1000 is used to create a first bone cavitygenerally along the axis of the IM canal. In a second step, a bushing1010 is slipped over the IM reamer 1000 and used to ream a second bonecavity generally coaxial with the cavity from the first step. In a thirdstep, a cylindrical reamer 1020 is slipped over the IM reamer 1000 andused to ream a third bone cavity generally coaxial to cavities from thefirst and second steps to prepare the bone to accept a diaphysealfemoral cone, such as diaphyseal femoral cone 1100 illustrated in FIG.11. If it is decided at this point that a metaphyseal femoral cone ismore appropriate, the diaphyseal femoral cone 1100 is not implanted andtwo further steps can be completed to prepare the bone to receive ametaphyseal femoral cone.

Referring now to FIGS. 12A-D, there are shown instruments used in thesecond group of steps described above. In a fourth step of a revisionprocedure, illustrated in FIGS. 12A-B, an offset driver 1200 is slippedover IM reamer 1000. Following this, in a fifth step illustrated inFIGS. 12C-D, a conical reamer 1210 is slipped over offset driver 1200(not visible in FIGS. 12C-D). The offset conical reamer 1210 can then beused to create conical bone cavities that have an axis offset from thebone cavities created in steps 1-3 described above. For example, a firstconical bone cavity can be created medial to the bone cavity created insteps 1-3. After adjusting the offset driver 1200 to a differentposition, a second conical bone cavity can be created lateral to thebone cavity created in steps 1-3. The conical bone cavities can becreated as necessary to form a complementary fit with a metaphysealfemoral cone, for example metaphyseal femoral cone 1300 illustrated inFIG. 13.

FIGS. 14-24 show other embodiment systems and methods for forming voidsin bone. Referring now to FIG. 14, the beginning of one method of arevision procedure is shown. For example, in a revision procedure of atotal knee replacement surgery, the initial step is to first ream thebone 1400 along the IM canal. Although an elongate IM reamer 1500 isillustrated as distally reaming the tibia beginning at the tibialplateau 1410, this is merely an example. The elongate IM reamer 1500could also be used to proximally ream the femur beginning at the distalend of the femur in substantially the same manner. FIG. 14 shows theelongate IM reamer 1500 following the initial reaming step. The elongateIM reamer 1500 includes an elongate IM reamer head 1520, which is shownpositioned within the IM canal, and an elongate reamer shaft 1510, whichis shown extending from the IM canal. The elongate IM reamer head 1520is used for reaming the IM canal and for firmly positioning the elongateIM reamer 1500 within bone 1400 to provide a stable platform for theelongate reamer shaft 1510 to accommodate further components in the kneerevision procedure.

FIG. 15 shows the first step following the initial tibial or femoral IMcanal preparation. The elongate IM reamer 1500 utilized to initiallyprepare the IM canal is left in place within the bone 1400 in order tosupport additional equipment utilized for forming bone voids. As shownin FIG. 15, a hollow inner cylinder of a cone reamer 1600 is slippedover the elongate IM reamer shaft 1510 to position a cone reamer head1620 coaxial with the elongate IM reamer 1500. The cone reamer head 1620is generally frustoconical, but may incorporate additional features toaccommodate the shape of a void filling implant. For example, a neck1640 may extend from the distal end of the cone reamer head 1620 inorder to form a similarly shaped void. The cone reamer 1600 alsoincludes a cone reamer shaft 1610. The cone reamer shaft 1610 isconfigured to be mechanically or manually driven. For example, theproximal end of the cone reamer shaft 1610 may be configured to beinserted into a drill chuck.

Once the cone reamer 1600 is placed over the elongate IM reamer shaft1510, a first reaming step is performed by mechanically or manuallyapplying a torque to the cone reamer 1600 to drive the cone reamer head1620 distally along the elongate IM reamer shaft to form a central bonevoid that is generally coaxial with the prepared IM canal. FIG. 16 showsthe positioning of the cone reamer head 1620 within the bone 1400following the first reaming step. As show in FIG. 16, the cone reamerhead 1620 is driven into the bone such that the proximal surface 1660 ofthe cone reamer head 1620 is flush with the tibial platform 1410. Inanother embodiment, the surgeon may choose to drive the cone reamer head1620 deeper into the bone 1400 so that the proximal surface of the conereamer head 1660 is distal to the tibial platform 1410. This may occurwhere a surgeon utilizes a tibial or femoral augment to accommodate amedial or lateral bone defect. In such a scenario the surgeon may drivethe cone reamer head 1620 deeper into the bone 1400 such that theproximal surface of the cone reamer head 1660 is flush with the proximalsurface of an augmented bone segment (not shown), but distal to thetibial platform 1410.

Referring now to FIG. 17A, the placement of a cone trial 1700 is shown.The cone reamer 1600 first is removed from the created bone void andfrom engagement with the elongate IM reamer 1500. With the elongate IMreamer remaining in place, a cone trial 1700 and a reamer guide shaft1800 are then slidably engaged with the elongate IM reamer shaft 1510.For example, the cone trial 1700 and reamer guide shaft 1800 may have ahollow inner cylinder that is placed over the elongate IM reamer shaft1510 in a slidable arrangement.

FIGS. 17B-C show a perspective view of the cone trial 1700 and thereamer guide shaft 1800, respectively. The cone trial 1700 is generallyfrustoconical in shape and includes an extraction feature 1730,anti-rotation splines 1710, at least one clearance groove 1720, and akeyway slot 1750. The cone trial 1700 may include other geometricfeatures to substantially match the central bone void. For example, thecone trial 1700 may include a cone trial neck 1740 extending from thedistal end of the cone trial 1700. The extraction feature 1730 appearsas a groove formed on the inner surface of the cone trial, which createsa ridge for engagement with an extraction device. One example of suchextraction device is the reamer guide shaft 1800. While this particularembodiment shows a groove forming the extraction feature 1730, otherfeatures not shown may be implemented that allow for the transmission ofan axial force to the trial cone 1700 in order to forcibly remove thetrial cone 1700 from the central bone void.

FIG. 17C shows a close-up view of the interrelation between the reamerguide shaft 1800 and cone trial 1700. The reamer guide shaft generallyincludes a reamer guide shaft body 1830, a reamer guide shaft impactionsurface 1810, a plurality of locking features 1840, an orientation key1870, and a depth indicator 1860. The impaction surface 1810 is locatedat the proximal end of the reamer guide shaft body 1830 and isconfigured to receive and evenly transmit impact forces in an axialdirection toward the cone trial 1700. The plurality of locking features1840 are shown as circular indents located on the outer surface of thereamer guide shaft body 1830 and axially aligned along the longitudinalaxis of the reamer guide shaft 1800. Also, located on the outer surfaceof the reamer guide shaft body is the depth indicator 1860, which isshown as a series of notches etched in the outer surface of the reamerguide shaft body 1830 along with corresponding indicator markings. Aretaining groove 1850 is shown intersecting the depth indicator in aproximal-distal direction.

Near the distal end of the reamer guide shaft is the orientation key1870, which appears as a protrusion extending radially from reamer guideshaft body 1830. The orientation key 1870 is shaped to tightly fit intothe orientation keyway slot 1720 of cone trial 1700 to prevent therotation of the reamer guide shaft 1800 and cone trial 1700 with respectto each other. The distal end of the reamer guide shaft 1800 isconfigured to partially fit within the cone trial 1700 and to mate withan internal ridge 1760 located therein. As shown, the diameter of theinternal ridge 1760 is narrower than the outside diameter of the reamerguide 1800, which facilitates a mating engagement in order to evenlytransfer impact forces from the impaction surface 1820 to the cone trial1700.

FIG. 18A shows an inserting step and preparation for a seating step.Once the reamer guide shaft 1800 and cone trial 1700 are placed over theelongate IM reamer 1500, the cone trial 1700 is then partially insertedwithin the central bone void using the reamer guide shaft 1800 such thatthe anti-rotation splines 1710 remain proximal of the tibial platform1410. A template guide 2000 and sizing template 1900 are then placedover the reamer guide shaft 1800.

FIG. 18B shows a perspective view of the template guide 2000 and sizingtemplate 1900. The template guide 2000 includes support arms 2020 thatselectively attach to the sizing template 1900. The sizing template 1900has a cavity 1910 that is coaxial with a template guide cavity 2010. Thetemplate guide 2000 facilitates manipulation of the sizing template 1900by the surgeon and also connects the sizing template 1900 to the reamerguide shaft 1800 to prevent rotation of the sizing template 1900 withrespect to the reamer guide shaft 1800.

Referring now to FIG. 19, a perspective view of a seating step is shown.As the sizing template 1900 and template guide 2000 are placed over thereamer guide shaft 1800, an engagement feature on the inner surface ofthe template guide cavity 2010 engages the retaining groove 1850 of thereamer guide shaft 1800. The engagement feature then comes to restagainst the distal edge of the retaining groove 1850. At this point, thesizing template 1900 and template guide 2000 are restrained from distaland rotational movement, but are free to move along the retaining groove1850 proximally. After sizing and setting the proper rotation, the conetrial 1700 is fully seated by applying impact force on the impactsurface 1810. This causes the anti-rotation splines 1710 to engage thebone, thereby preventing rotational movement of the cone trial 1700 withrespect to the bone 1400. The appropriate driving depth of the trialcone 1700 is determined by viewing a proximal plateau 2030 of thetemplate guide 2000 in relation to the depth indicator 1860 of thereamer guide shaft 1800. As the trial cone 1700 is driven deeper intothe bone 1400, the tibial platform 1410 will engage and push the sizingtemplate 1900 and template guide 2000 proximally along the retaininggroove 1850. When the proximal plateau 2030 lines up with the depthappropriate markings, the surgeon knows the proper depth has beenreached. For example, the reamer guide shaft 1800 may provide threedepths based upon whether a tibial augment is used and the size of theaugment. Where no augment is utilized, the cone trial 1700 is driveninto the bone 1400 such that the proximal surface of the cone trial 1700is either flush with the tibial platform 1410 or approximately 1-3 mmdistal of the tibial platform, which in this example would be where theproximal plateau 2030 would line up with the most distal marking of thedepth indicator 1860, which is designated as “N”. Once the cone trial1700 is fully seated within the bone 1400, the template guide 2000 andsizing template 1900 are removed so that the reamer guide shaft 1800 canbe prepared for a second reaming step.

FIGS. 20A-B illustrate an offset lobe reamer 2200 and offset lobe reamerretainer 2100 and their preparation for the second reaming step to forma first offset lobe void adjacent to the central bone void. Referringnow to FIG. 20A, the offset lobe reamer retainer 2100 includes an offsetlobe reamer retainer body 2140 that may be cylindrically hollow, anoffset lobe reamer guide 2120 attached to the offset lobe reamer body2140 by a flange 2130, and a locking mechanism 2110. The offset lobereamer guide 2120 has a longitudinal axis that offset from the axis ofthe IM canal. The offset lobe reamer 2200 includes an offset lobe reamershaft 2210, an offset lobe reamer head 2220 located at the distal end ofthe offset lobe reamer shaft 2210, and a depth stop 2230 near theproximal end of the lobe reamer shaft 2210. The proximal end of theoffset lobe reamer 2200 is configured to be manually or mechanicallyoperated. The offset lobe reamer 2200 is initially prepared by slidablyengaging the offset lobe reamer shaft 2210 with the offset lobe reamerguide 2120.

Referring to FIG. 20B, the offset lobe reamer retainer body 2140 is thenplaced over the reamer guide shaft 1800 such that the offset lobe reamerhead 2220 faces the bone 1400. The offset lobe reamer retainer 2100 isthen locked at the proper location, which correspondingly fixes thelongitudinal axis of the lobe reamer guide 2120 with respect to thelongitudinal axis of the IM canal. An example of the locking mechanism2110 is a wingnut that provides a locked connection to the reamer guideshaft 1800, whereby the threaded screw portion of the locking wingnutengages the circular indents of the locking features 1840. The properlocation is determined by selecting a locking position corresponding toa predetermined locking feature 1840 of the reamer guide shaft 1800. Theparticular embodiment shown in FIGS. 17C and 20A illustrate fourseparate locking features 1840, each corresponding to the desired sizeof the first offset lobe void. For instance, the locking features 1840may be designated small, medium, large, and extra-large with the mostproximal locking component 1840 being small and most distal beingextra-large. The more distal the offset lobe reamer retainer 2100 islocked, the further the axis of the first offset lobe void will be fromthe axis of the central bone void. It is also possible to vary the sizeof the flange 2130, rather than the locking position to achieve similarresults.

FIG. 21 shows the completion of a second reaming step. Once the offsetlobe reamer retainer 2100 is locked in the proper position, the surgeoncan drive, either mechanically or manually, the offset lobe reamer head2220 into the bone 1400, thereby reaming the first offset lobe voidadjacent to the central bone void. The proper depth of the first offsetlobe void can be achieved when the depth stop 2230 abuts the proximaledge of the offset reamer guide 2120, thereby preventing further distalreaming. The first offset lobe void that is formed by the particularembodiment shown in FIG. 21 is integrated with the central bone void toprovide the appearance of one continuous void. This is achieved by theclearance grooves 1720 of the cone trial 1700. This feature providesclearance so that the offset lobe reamer head 2220 is able to breach thewall of bone formed by the central bone void in order to integrate thevoids. Once the first offset bone void is formed, a second offset bonevoid may be created by repeating the second reaming step on the oppositeside of the central bone void. Such first and/or second offset bone voidmay be desirable where there is a bone deformity adjacent to the centralbone void. Reaming offset lobe voids would remove the deformity andleave a precisely formed void to be filled with a bone void filler, suchas a cone (discussed below), to provide structural integrity to the bone1400.

After the desired bone void has been created, the elongate IM reamer1500 and reaming equipment is removed from the bone 1400. A desired coneis then selected for insertion into the corresponding bone void. FIGS.22-23 illustrate two separate embodiments of the multitude of cones thatmay be selected. FIGS. 23A-F show a conical cone 2300 that is generallyfrustoconical in shape, but may include a conical cone neck 2320extending from the distal end of the conical cone 2300 to improvestability. Referring to FIGS. 22A-B, the conical cone 2300 is shown in atop view and front view, respectively. The conical cone 2300 generallyincludes a central opening 2350 to accommodate a prosthesis stem 2520and at least one clearance channel 2310 to accommodate a baseplate keel2510. The interior space of the conical cone 2300 formed by the centralopening 2350 may be packed with bone cement or other adhesive in orderto enhance connection between the prosthesis and bone 1400. Thisenhanced connection is further improved by an adhesive anti-rotationfeature 2340 located on the interior surface of the conical cone 2360.For example, the adhesive anti-rotation feature 2340 may be a series ofprotrusions extending from the interior surface of the conical cone 2360to prohibit rotation of the adhesive with respect to the conical cone2300. The conical cone 2300 may be constructed of any implant-gradematerial. For example, the interior surface of the conical cone 2360 maybe constructed of solid titanium, and the exterior surface 2370constructed of porous titanium to enhance binding bone growth. Anotherexample would be where the conical cone 2300 varies in density such thatthe density decreases from a dense inner surface to a porous outersurface, which would allow for greater bone growth on the outer surface.

FIGS. 22C-D show a front and side view, respectively, demonstrating theinterrelation of the conical cone clearance channel 2310 and baseplatekeel 2510.

FIGS. 22E-F show transparent views of the interrelation between theconical cone 2300 and baseplate keel 2510 where the conical cone 2300 isimplanted at differing bone depths. FIG. 22E illustrates theinterrelation where the conical cone 2300 is deep within the bone 1400.This would typically occur where the surgeon utilizes augments tocompensate for bone deformities.

FIG. 22F illustrates the interrelation where the conical cone 2300 isinserted into the central bone void such that the proximal surface ofthe conical cone 2300 is flush with the tibial platform 1410.

FIGS. 23A-G illustrate another cone embodiment. Referring now to FIGS.23A-C, a perspective, top and front view, respectively, of a lobed cone2400 is shown. The lobed cone 2400 generally includes a central opening2450 to accommodate a prosthesis stem 2520, a clearance channel 2420 toaccommodate a baseplate keel 2510, a conical body 2480, and a lobe 2410integrated with the conical body 2480. The interior space of the lobedcone 2400 may be packed with bone cement or other adhesive in order toenhance connection between the prosthesis and bone 1400. This enhancedconnection is further improved by an adhesive anti-rotation feature 2450located on the interior surface of the lobed cone 2460. For example, theadhesive anti-rotation feature 2450 may include a series of protrusionsextending from the interior surface of the lobed cone 2460 to prohibitrotation of the adhesive with respect to the lobed cone 2400. The lobedcone 2400 may be constructed of any implant-grade material. For example,the interior surface of the lobed cone 2460 may be constructed of solidtitanium, and the exterior surface 2470 constructed of porous titaniumto enhance binding bone growth. Another example would be where the lobedcone 2460 varies in density such that the density decreases from a denseinner surface to a porous outer surface, which would allow for greaterbone growth on the outer surface.

Further, the lobe 2430 may include a window 2430. The window 2430 isessentially a clearance channel 2420 that has been covered by the poroustitanium of the outer surface 2470. This provides the surgeon theflexibility to open the window 2430 by cutting out the porous titaniumwith standard surgical tools or a specialized tool, thereby creating anadditional clearance window 2420 in the event clearance space is neededfor a larger baseplate keel 2510. Where additional clearance space isnot needed, the porous titanium remains to provide additional surfacearea for binding bone growth.

FIG. 23D is a bottom view illustrating the interrelation of the lobedcone 2400 with the baseplate 2500 and baseplate keel 2510, and inparticular the interrelation of the baseplate keel 2510 with the lobe2410 and clearance channel 2420.

FIGS. 23E-F show transparent views of the interrelation between thelobed cone 2400 and baseplate keel 2510 depending on the depth of thelobed cone 2400 within the bone 1400. FIG. 22E illustrates thisinterrelation where the lobed cone 2400 is deep within the bone 1400.This would typically occur where the surgeon utilizes augments tocompensate for bone deformities.

FIG. 23F illustrates the interrelation where the lobed cone 2400 isinserted into the central bone void and offset bone void such that theproximal surface of the lobed cone 2400 is flush with the tibialplatform 1410.

FIG. 23G shows the prosthesis being inserted into the lobed cone 2400and bone for final implantation. The stem 2600 passes through thecentral opening 2450 and into the intramedullary canal. When fullyinserted, the baseplate 2500 will rest proximally to the lobed coned2400 with the baseplate keel 2510 residing partially within the lobedcone 2400. Generally, the lobed cone 2400 will be filled with adhesiveto provide further support to the prosthesis.

There are many benefits of performing a revision procedure with thesurgical reaming instruments of the present invention. For example, allbone removal steps may be fully guided without the need for any freehandbone removal. Additionally, the surgeon is left with the option tocreate an offset bone cavity by reaming the bone in three steps orbroaching the bone in only two steps. Importantly, because of theprecision of control allowed when using these instruments, the shape ofthe cavity can be precisely controlled which allows for stock MRDs/conesto accurately fit into the bone void without dependence on the techniqueof the particular surgeon performing the surgery. Related to this isthat the symmetric, geometrically defined shape of an MRD/conesimplifies the setup and machining of void fillers. The MRDs/conesdescribed herein can be made of any biocompatible material such aspolymer, titanium, and stainless steel, for example.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims. For example,although embodiments of the invention have generally been described inreference to a femoral implant in a femur or with respect to a tibia,the principles described herein are equally applicable to bones of otherjoints.

1. A method of performing a revision arthroplasty of a proximal tibiacomprising: reaming the proximal tibia with a first cone reamer to forma first frustoconical void; reaming the proximal tibia with a secondcone reamer assembly to form a second frustoconical void intersectingwith the first frustoconical void; implanting a lobed cone into thefirst and second frustoconical voids, the lobed cone having afrustoconical body and a lobe portion, the frustoconical bodycorresponding with the first frustoconical void and having an openingextending therethrough, the lobe portion extending from thefrustoconical body and corresponding with the second frustoconical void;and implanting a tibial prosthesis such that a stem portion thereofextends through the opening and into an intramedullary canal.
 2. Themethod of claim 1, further comprising at least partially inserting adistal cone portion of the second cone reamer assembly into the firstfrustoconical void such that anti-rotation splines located on an outersurface of the distal cone portion engage bone defining the firstfrustoconical void.
 3. The method of claim 1, wherein implanting thetibial prosthesis includes inserting a keel thereof into the lobeportion such that the keel is at least partially retained therein andinserting the keel into and through a clearance notch in thefrustoconical body of the lobe cone such that the keel extends from theclearance notch into bone adjacent the first frustoconical void.
 4. Themethod of claim 3, further comprising placing bone cement into thefrustoconical body and lobe portion prior to the step of implanting thetibial prosthesis.
 5. The method of claim 4, further comprising placingbone cement into the first and second frustoconical voids prior toimplanting the lobed cone therein.
 6. The method of claim 1, wherein theopening through the frustoconical body extends transversely into thelobe portion and terminates within the lobe portion at a distal floor.7. A method of performing a revision arthroplasty of a proximal tibiacomprising: reaming along an elongate rod extending from the proximaltibia with a first reamer to form a first void; sliding a reamerassembly over the elongate rod such that a second reamer moveablyattached to the reamer assembly is offset from the elongate rod; reamingalong the reamer assembly into the proximal tibia with the second reamerto form a second void intersecting with the first void; implanting avoid filling prosthesis having first and second portions and an openingextending therethrough into the first and second voids such that thefirst portion is disposed within the first void and the second portionis disposed in the second void; and implanting a tibial prosthesis suchthat a stem portion thereof extends through the opening and into theintramedullary canal.
 8. The method of claim 7, further comprisingreaming an intramedullary canal of the tibia with an intramedullaryreamer, and wherein the intramedullary reamer comprises the elongaterod.
 9. The method of claim 7, further comprising inserting bone cementinto the void filling prosthesis prior to implanting the tibialprosthesis.
 10. The method of claim 9, wherein the opening extendsentirely through the first portion and extends transversely from thefirst portion into the second portion, and inserting bone cement intothe void filling prosthesis includes placing bone cement into theopening within the first and second portions.
 11. The method of claim 7,wherein implanting the tibial prosthesis includes inserting a keelmember into the opening of the void filling prosthesis such that thekeel member is at least partially retained therein and inserting thekeel member into and through a clearance notch formed in a sidewall ofthe first portion such that the keel member extends from the clearancenotch into bone adjacent the first portion.
 12. The method of claim 7,further comprising removing a previously implanted tibial prosthesisfrom the proximal tibia.
 13. The method of claim 7, wherein reaming withthe first reamer includes sliding the first reamer over the elongaterod.
 14. A method of performing a revision arthroplasty of a proximaltibia comprising: sliding a reamer assembly over an elongate rodextending from a proximal tibia; inserting a conical portion of thereamer assembly into a corresponding first void in the proximal tibia,the reamer assembly having an elongate shaft extending from the conicalportion; driving a reamer into the proximal tibia to form a second voidintersecting with the first void, the reamer being supported by a reamerguide connected to the elongate shaft; implanting first and secondportions of a void filling prosthesis into the first and second voids,respectively, the first portion at least partially defining an openingextending therethrough; and implanting a tibial prosthesis such that astem portion thereof extends through the opening and into theintramedullary canal.
 15. The of claim 14, further comprising: sliding areamer over the elongate rod; and reaming the first void.
 16. The ofclaim 14, further comprising packing bone cement within the opening ofthe void filling prosthesis.
 17. The of claim 14, wherein the implantingstep includes inserting a keel of the tibial prosthesis into the secondportion of the void filling prosthesis such that the keel is obscuredfrom contact with the proximal tibia.
 18. The of claim 14, wherein thevoid filler consists essentially of the first and second portions. 19.The of claim 18, wherein the first portion is a conical body and thesecond portion is a conical lobe extending from one side of the conicalbody.
 20. The of claim 19, wherein the conical body defines a clearancechannel configure to receive a keel of the tibial prosthesis.